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Carboxylic Acids and Derivatives - Organic Chemistry

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이 집합의 용어 (20)

  • How are carboxylic acids prepared from Grignard reagents?
    Treat a Grignard reagent with carbon dioxide to form a magnesium carboxylate salt, then protonate with aqueous acid to obtain the carboxylic acid.
  • What reagent reduces carboxylic acids to primary alcohols?
    Lithium aluminum hydride (LiAlH4) reduces carboxylic acids to 1° alcohols in ether or THF.
  • How can aldehydes or ketones be selectively reduced in the presence of carboxylic acids?
    Use sodium borohydride (NaBH4), which reduces aldehydes and ketones but not carboxylic acids.
  • What is Fischer esterification?
    Preparation of esters by treating a carboxylic acid with an alcohol in the presence of an acid catalyst like H2SO4.
  • How are acid chlorides typically prepared?
    By treating carboxylic acids with thionyl chloride (SOCl2).
  • What determines the relative reactivity of carboxylic acid derivatives toward nucleophilic acyl substitution?
    Leaving group ability and resonance stabilization; weaker bases are better leaving groups, increasing reactivity.
  • Order the reactivity of carboxylic acid derivatives from most to least reactive.
    Acid halides > acid anhydrides > esters > amides.
  • What are the three main types of reactions for carboxylic acid derivatives?
    Hydrolysis (to carboxylic acid), alcoholysis (to ester), and aminolysis (to amide).
  • How do acid chlorides react with water?
    They hydrolyze rapidly to form carboxylic acids and HCl without needing acid or base catalysis.
  • Describe the hydrolysis of esters under acidic conditions.
    Acid-catalyzed ester hydrolysis is reversible and involves protonation of the carbonyl, nucleophilic attack by water, and loss of the alcohol group.
  • What is the difference between acid and base hydrolysis of esters?
    Acid hydrolysis is reversible and catalytic; base hydrolysis is irreversible and requires stoichiometric base.
  • How are amides hydrolyzed in aqueous base?
    Hydroxide ion attacks the carbonyl carbon, forming a tetrahedral intermediate that expels the amide anion, which is then protonated.
  • What products form when acid halides react with alcohols?
    Esters are formed; no catalyst is needed due to high reactivity of acid halides.
  • What is transesterification?
    The acid-catalyzed reaction of an ester with an alcohol, which is an equilibrium process that can be driven by changing conditions.
  • Do amides react with alcohols under normal conditions?
    No, amides are the least reactive carboxylic acid derivatives and do not react with alcohols.
  • How do acid halides react with ammonia or amines?
    They form amides; two moles of ammonia or amine are needed—one to form the amide and one to neutralize the HCl formed.
  • Describe the reaction of esters with Grignard reagents.
    One mole of Grignard reagent forms a ketone intermediate, which reacts with a second mole to give a tertiary alcohol after hydrolysis.
  • What reagent reduces esters to two alcohols?
    Lithium aluminum hydride (LiAlH4) reduces esters to a primary alcohol and an alcohol derived from the alkoxy group.
  • What is the role of diisobutylaluminum hydride (DIBALH) in ester reduction?
    DIBALH reduces esters to aldehydes at low temperature (−78°C), allowing selective partial reduction.
  • What products result from LiAlH4 reduction of amides?
    Primary, secondary, or tertiary amines depending on the amide substitution.